Linux Distros Unpatched Vulnerability : CVE-2026-81736

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(346494);
  script_version("1.5");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/09/19");

  script_cve_id("CVE-2026-81736");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2026-81736");

  script_set_attribute(attribute:"synopsis", value:
"The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be
patched.");
  script_set_attribute(attribute:"description", value:
"The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied
patch available.

  - If a BIND resolver has cached a tree of SVCB/HTTPS AliasMode records, and is then queried for the root of
    that tree, the resolver will spend disproportionate CPU time constructing the response. This issue affects
    BIND 9 versions 9.18.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.18.11-S1 through
    9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1. (CVE-2026-81736)

Note that Nessus relies on the presence of the package as reported by the vendor.");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/security/cve/cve-2026-81736");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2026-81736");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2026-81736");
  script_set_attribute(attribute:"solution", value:
"There is no known solution at this time.");
  script_set_attribute(attribute:"agent", value:"unix");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:U/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:U/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2026-81736");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_set_attribute(attribute:"vendor_unpatched", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2026/09/16");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/09/16");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:14.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:16.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:20.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:22.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:24.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:26.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:12.0");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:10");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:9");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:bind9");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:bind9-libs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:isc-dhcp");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:bind9");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:bind");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:bind-chroot");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:bind-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:bind-dnssec-utils");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:bind-doc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:bind-libs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:bind-license");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:bind-utils");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:bind9.18");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:bind9.18-chroot");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:bind9.18-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:bind9.18-dnssec-utils");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:bind9.18-doc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:bind9.18-libs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:bind9.18-utils");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Misc.");

  script_copyright(english:"This script is Copyright (C) 2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info2.nasl", "set_linux_os_id.nasl");
  script_require_keys("Host/cpu", "Host/local_checks_enabled", "global_settings/vendor_unpatched", "Host/OS/identifier");
  script_require_ports("Host/OS/Debian Linux-12", "Host/OS/Red Hat Enterprise Linux-10", "Host/OS/Red Hat Enterprise Linux-9", "Host/OS/Ubuntu Linux-14.04", "Host/OS/Ubuntu Linux-16.04", "Host/OS/Ubuntu Linux-18.04", "Host/OS/Ubuntu Linux-20.04", "Host/OS/Ubuntu Linux-22.04", "Host/OS/Ubuntu Linux-24.04", "Host/OS/Ubuntu Linux-26.04");

  exit(0);
}

if (!get_kb_item("global_settings/vendor_unpatched")) exit(0, "Unpatched Vulnerabilities Detection not active.");
if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (empty_or_null(get_one_kb_item("Host/Debian/dpkg-l")) && empty_or_null(get_one_kb_item("Host/RedHat/rpm-list"))) audit(AUDIT_PACKAGE_LIST_MISSING);

include('linux_unpatched.inc');

var distro_constraints_array = {
  "Debian Linux-12": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "12",
        "pkgs": [
          {"reference": "bind9"},
          {"reference": "bind9-dev"},
          {"reference": "bind9-dnsutils"},
          {"reference": "bind9-doc"},
          {"reference": "bind9-host"},
          {"reference": "bind9-libs"},
          {"reference": "bind9-utils"},
          {"reference": "bind9utils"},
          {"reference": "dnsutils"}
        ]
      }
    ]
  },
  "Ubuntu Linux-14.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "14.04",
        "pkgs": [
          {"reference": "bind9"},
          {"reference": "bind9-doc"},
          {"reference": "bind9-host"},
          {"reference": "bind9utils"},
          {"reference": "dnsutils"},
          {"reference": "host"},
          {"reference": "libbind-dev"},
          {"reference": "libbind9-90"},
          {"reference": "libdns100"},
          {"reference": "libisc95"},
          {"reference": "libisccc90"},
          {"reference": "libisccfg90"},
          {"reference": "liblwres90"},
          {"reference": "lwresd"}
        ]
      }
    ]
  },
  "Ubuntu Linux-16.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "16.04",
        "pkgs": [
          {"reference": "bind9"},
          {"reference": "bind9-doc"},
          {"reference": "bind9-host"},
          {"reference": "bind9utils"},
          {"reference": "dnsutils"},
          {"reference": "host"},
          {"reference": "libbind-dev"},
          {"reference": "libbind-export-dev"},
          {"reference": "libbind9-140"},
          {"reference": "libdns-export162"},
          {"reference": "libdns-export162-udeb"},
          {"reference": "libdns162"},
          {"reference": "libirs-export141"},
          {"reference": "libirs-export141-udeb"},
          {"reference": "libirs141"},
          {"reference": "libisc-export160"},
          {"reference": "libisc-export160-udeb"},
          {"reference": "libisc160"},
          {"reference": "libisccc-export140"},
          {"reference": "libisccc-export140-udeb"},
          {"reference": "libisccc140"},
          {"reference": "libisccfg-export140"},
          {"reference": "libisccfg-export140-udeb"},
          {"reference": "libisccfg140"},
          {"reference": "liblwres141"},
          {"reference": "lwresd"}
        ]
      }
    ]
  },
  "Ubuntu Linux-18.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "18.04",
        "pkgs": [
          {"reference": "bind9"},
          {"reference": "bind9-doc"},
          {"reference": "bind9-host"},
          {"reference": "bind9utils"},
          {"reference": "dnsutils"},
          {"reference": "isc-dhcp-client"},
          {"reference": "isc-dhcp-client-ddns"},
          {"reference": "isc-dhcp-client-udeb"},
          {"reference": "isc-dhcp-common"},
          {"reference": "isc-dhcp-dev"},
          {"reference": "isc-dhcp-relay"},
          {"reference": "isc-dhcp-server"},
          {"reference": "isc-dhcp-server-ldap"},
          {"reference": "libbind-dev"},
          {"reference": "libbind-export-dev"},
          {"reference": "libbind9-160"},
          {"reference": "libdns-export1100"},
          {"reference": "libdns-export1100-udeb"},
          {"reference": "libdns1100"},
          {"reference": "libirs-export160"},
          {"reference": "libirs-export160-udeb"},
          {"reference": "libirs160"},
          {"reference": "libisc-export169"},
          {"reference": "libisc-export169-udeb"},
          {"reference": "libisc169"},
          {"reference": "libisccc-export160"},
          {"reference": "libisccc-export160-udeb"},
          {"reference": "libisccc160"},
          {"reference": "libisccfg-export160"},
          {"reference": "libisccfg-export160-udeb"},
          {"reference": "libisccfg160"},
          {"reference": "liblwres160"}
        ]
      }
    ]
  },
  "Ubuntu Linux-20.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "20.04",
        "pkgs": [
          {"reference": "bind9"},
          {"reference": "bind9-dnsutils"},
          {"reference": "bind9-doc"},
          {"reference": "bind9-host"},
          {"reference": "bind9-libs"},
          {"reference": "bind9-utils"},
          {"reference": "bind9utils"},
          {"reference": "dnsutils"},
          {"reference": "libbind-dev"},
          {"reference": "libbind-export-dev"},
          {"reference": "libbind9-161"},
          {"reference": "libdns-export1109"},
          {"reference": "libdns-export1109-udeb"},
          {"reference": "libdns1109"},
          {"reference": "libirs-export161"},
          {"reference": "libirs-export161-udeb"},
          {"reference": "libirs161"},
          {"reference": "libisc-export1105"},
          {"reference": "libisc-export1105-udeb"},
          {"reference": "libisc1105"},
          {"reference": "libisccc-export161"},
          {"reference": "libisccc-export161-udeb"},
          {"reference": "libisccc161"},
          {"reference": "libisccfg-export163"},
          {"reference": "libisccfg-export163-udeb"},
          {"reference": "libisccfg163"},
          {"reference": "liblwres161"}
        ]
      }
    ]
  },
  "Ubuntu Linux-22.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "22.04",
        "pkgs": [
          {"reference": "bind9"},
          {"reference": "bind9-dev"},
          {"reference": "bind9-dnsutils"},
          {"reference": "bind9-doc"},
          {"reference": "bind9-host"},
          {"reference": "bind9-libs"},
          {"reference": "bind9-utils"},
          {"reference": "bind9utils"},
          {"reference": "dnsutils"},
          {"reference": "libbind-dev"},
          {"reference": "libbind-export-dev"},
          {"reference": "libbind9-161"},
          {"reference": "libdns-export1110"},
          {"reference": "libdns-export1110-udeb"},
          {"reference": "libdns1110"},
          {"reference": "libirs-export161"},
          {"reference": "libirs-export161-udeb"},
          {"reference": "libirs161"},
          {"reference": "libisc-export1105"},
          {"reference": "libisc-export1105-udeb"},
          {"reference": "libisc1105"},
          {"reference": "libisccc-export161"},
          {"reference": "libisccc-export161-udeb"},
          {"reference": "libisccc161"},
          {"reference": "libisccfg-export163"},
          {"reference": "libisccfg-export163-udeb"},
          {"reference": "libisccfg163"},
          {"reference": "liblwres161"}
        ]
      }
    ]
  },
  "Ubuntu Linux-24.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "24.04",
        "pkgs": [
          {"reference": "bind9"},
          {"reference": "bind9-dev"},
          {"reference": "bind9-dnsutils"},
          {"reference": "bind9-doc"},
          {"reference": "bind9-host"},
          {"reference": "bind9-libs"},
          {"reference": "bind9-utils"},
          {"reference": "bind9utils"},
          {"reference": "dnsutils"},
          {"reference": "isc-dhcp"}
        ]
      }
    ]
  },
  "Ubuntu Linux-26.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "26.04",
        "pkgs": [
          {"reference": "bind9"},
          {"reference": "bind9-dev"},
          {"reference": "bind9-dnsutils"},
          {"reference": "bind9-doc"},
          {"reference": "bind9-host"},
          {"reference": "bind9-libs"},
          {"reference": "bind9-utils"},
          {"reference": "isc-dhcp"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-10": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "10",
        "pkgs": [
          {"reference": "bind"},
          {"reference": "bind-chroot"},
          {"reference": "bind-devel"},
          {"reference": "bind-dnssec-utils"},
          {"reference": "bind-doc"},
          {"reference": "bind-libs"},
          {"reference": "bind-license"},
          {"reference": "bind-utils"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-9": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "9",
        "pkgs": [
          {"reference": "bind9.18"},
          {"reference": "bind9.18-chroot"},
          {"reference": "bind9.18-devel"},
          {"reference": "bind9.18-dnssec-utils"},
          {"reference": "bind9.18-doc"},
          {"reference": "bind9.18-libs"},
          {"reference": "bind9.18-utils"}
        ]
      }
    ]
  }
};

var distro_constraints_values = linux_unpatched::get_distro_constraints(distro_constraints_arr:distro_constraints_array);
if (empty_or_null(distro_constraints_values)) audit(AUDIT_HOST_NOT, 'affected');

var third_party_support = get_kb_item('Host/OS/extended-third-party');
if (!empty_or_null(third_party_support)) {
    var third_party_vendors = distro_constraints_values['third_party'];
    if (!empty_or_null(third_party_vendors)) {
        var vendor;
        foreach vendor (third_party_vendors) {
            if (vendor == third_party_support) exit(0, 'A third party management patch is available for this vulnerability from ' + vendor + '.\n');
        }
    }
}

var report = linux_unpatched::check_unpatched_constraints(distro_constraints_values:distro_constraints_values);

if (!empty_or_null(report))
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_WARNING,
      extra      : report
  );
  exit(0);
}
else
{
  audit(AUDIT_HOST_NOT, 'affected');
}